Flu jabs slash older people's risk of suffering a heart attack or stroke, according to new research.

The vaccinations cut heart attacks by up to 85 percent - and halve the number of strokes, say scientists.

A study of high risk hospital patients also found deaths from any cause fell by almost three quarters among protected over 50s.

It was based on more than seven million patients - one of the largest of its kind.

Most people in England are to be offered it free this year because of the pandemic.

Lead author Roshni Mandania, a medical candidate at Texas Tech University, Dallas, said: "The results we found are staggering.

"It's hard to ignore the positive effect the flu vaccine can have on serious cardiac complications.

"Some people don';t view flu vaccinations as necessary or important, and many may face barriers accessing health care including receiving the flu vaccine."

Being immunised against flu helps prevent chest infections - which weakens the immune system.

But take up among high risk groups - such as over 50s and care home residents - is extremely low.

So Ms Mandania's team compared its impact between the 168,325 participants who got vaccinated, and the vast majority who did not.

Immunised over 50s were 85 and 28 percent less likely to suffer a cardiac arrest or heart attack - caused by electrical and circulatory problems in the organ, respectively.

They also had a 47 percent lower risk of a mini stroke, or TIA (transient ischaemic attack). Overall, mortality rates fell by 73 percent.

The stress flu puts on the body is well known - and can cause a heart attack or stroke, explained the researchers.

But a virtual American Heart Association meeting was told this group was much less likely to be vaccinated compared to the general population - 1.8 versus 15.3 per cent.

Vaccination rates for HIV/AIDS patients, care home residents and the obese was also around two percent - compared to roughly nine percent for others.

Ms Mandania said: "These groups should have the highest vaccination rates because they are the most at risk.

"As health care providers, we must do everything we can to ensure our most vulnerable populations are protected against the flu and its serious complications."

She used the 2014 National In-patient Sample to assess the rate at which the jab was administered to those considered high risk for flu and its complications.

Dr Eduardo Sanchez, the American Heart Association's chief medical officer for prevention, said most people should be vaccinated each year.